1. Field of the Invention
The invention relates to a microwave generator, comprising a housing having two mutually opposite electrodes which are separated via an electrode intermediate space which is filled with a dielectric, and with the electrodes having a spark gap between them, which breaks down in order to emit microwaves when a high voltage is applied.
2. Discussion of the Prior Art
The operation of a microwave generator such as this is based on the short-circuiting, and thus discharging, of a high-voltage store, for example a capacitor structure, which is charged via a high-voltage supply, for example in the form of a Marx generator, via a spark gap. The short circuit results in highly oscillating discharge or short-circuit currents with a steep flank, which contain a mixture of very high frequencies which, as a rule, are emitted via an antenna as microwave energy with a broadband spectrum that is dependent on the frequency mixture. This broadband microwave spectrum has a sufficiently high energy density that the radio traffic in the area surrounding a microwave generator such as this is at least adversely affected, and input circuits of electronic circuits can be subjected to interference, or even destroyed, as a result of resonance effects.
The emission of the microwaves is based on a discharge-dependent resonance affect. The triggering electrodes between which the spark gap is formed are associated with further resonating electrode or conductor structures in which the discharge current pulse that is produced by the flashover leads to powerful sudden oscillations whose frequency mixture is a resonant peak based on the instantaneous electrically effective geometry of the resonator or of the resonator structure.
In one known embodiment of a microwave generator of the type mentioned initially, the two triggering electrodes, which are arranged coaxially, of the spark gap are connected to large-area electrodes which are in the form of spherical caps and form the antenna, with their curvatures facing one another. The two flat electrodes or antenna electrodes enclose an intermediate space between them, which is bounded at the side by the generator housing and in which a dielectric, generally a gaseous or liquid dielectric, is provided. This dielectric governs the capacitance and thus the resonant frequency of the antenna electrode structure and, in this way, the emitted frequency or the frequency spectrum of the high-power microwaves. As a result of the capacitively invariant design of the resonator structure comprising the antenna electrodes, this frequency spectrum cannot be varied.